1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
//! Extension traits and other utilities to make working with subscribers more
//! ergonomic.
use core::fmt;
#[cfg(feature = "std")]
use std::error::Error;
use tracing_core::dispatcher::{self, Dispatch};
#[cfg(feature = "tracing-log")]
use tracing_log::AsLog;
/// Extension trait adding utility methods for subscriber initialization.
///
/// This trait provides extension methods to make configuring and setting a
/// [default subscriber] more ergonomic. It is automatically implemented for all
/// types that can be converted into a [trace dispatcher]. Since `Dispatch`
/// implements `From<T>` for all `T: Subscriber`, all `Subscriber`
/// implementations will implement this extension trait as well. Types which
/// can be converted into `Subscriber`s, such as builders that construct a
/// `Subscriber`, may implement `Into<Dispatch>`, and will also receive an
/// implementation of this trait.
///
/// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
/// [trace dispatcher]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html
pub trait SubscriberInitExt
where
Self: Into<Dispatch>,
{
/// Sets `self` as the [default subscriber] in the current scope, returning a
/// guard that will unset it when dropped.
///
/// If the "tracing-log" feature flag is enabled, this will also initialize
/// a [`log`] compatibility layer. This allows the subscriber to consume
/// `log::Record`s as though they were `tracing` `Event`s.
///
/// [default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
/// [`log`]: https://crates.io/log
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
fn set_default(self) -> dispatcher::DefaultGuard {
#[cfg(feature = "tracing-log")]
let _ = tracing_log::LogTracer::init();
dispatcher::set_default(&self.into())
}
/// Attempts to set `self` as the [global default subscriber] in the current
/// scope, returning an error if one is already set.
///
/// If the "tracing-log" feature flag is enabled, this will also attempt to
/// initialize a [`log`] compatibility layer. This allows the subscriber to
/// consume `log::Record`s as though they were `tracing` `Event`s.
///
/// This method returns an error if a global default subscriber has already
/// been set, or if a `log` logger has already been set (when the
/// "tracing-log" feature is enabled).
///
/// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
/// [`log`]: https://crates.io/log
fn try_init(self) -> Result<(), TryInitError> {
dispatcher::set_global_default(self.into()).map_err(TryInitError::new)?;
// Since we are setting the global default subscriber, we can
// opportunistically go ahead and set its global max level hint as
// the max level for the `log` crate as well. This should make
// skipping `log` diagnostics much faster.
#[cfg(feature = "tracing-log")]
tracing_log::LogTracer::builder()
// Note that we must call this *after* setting the global default
// subscriber, so that we get its max level hint.
.with_max_level(tracing_core::LevelFilter::current().as_log())
.init()
.map_err(TryInitError::new)?;
Ok(())
}
/// Attempts to set `self` as the [global default subscriber] in the current
/// scope, panicking if this fails.
///
/// If the "tracing-log" feature flag is enabled, this will also attempt to
/// initialize a [`log`] compatibility layer. This allows the subscriber to
/// consume `log::Record`s as though they were `tracing` `Event`s.
///
/// This method panics if a global default subscriber has already been set,
/// or if a `log` logger has already been set (when the "tracing-log"
/// feature is enabled).
///
/// [global default subscriber]: https://docs.rs/tracing/0.1.21/tracing/dispatcher/index.html#setting-the-default-subscriber
/// [`log`]: https://crates.io/log
fn init(self) {
self.try_init()
.expect("failed to set global default subscriber")
}
}
impl<T> SubscriberInitExt for T where T: Into<Dispatch> {}
/// Error returned by [`try_init`](SubscriberInitExt::try_init) if a global default subscriber could not be initialized.
pub struct TryInitError {
#[cfg(feature = "std")]
inner: Box<dyn Error + Send + Sync + 'static>,
#[cfg(not(feature = "std"))]
_p: (),
}
// ==== impl TryInitError ====
impl TryInitError {
#[cfg(feature = "std")]
fn new(e: impl Into<Box<dyn Error + Send + Sync + 'static>>) -> Self {
Self { inner: e.into() }
}
#[cfg(not(feature = "std"))]
fn new<T>(_: T) -> Self {
Self { _p: () }
}
}
impl fmt::Debug for TryInitError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
#[cfg(feature = "std")]
{
fmt::Debug::fmt(&self.inner, f)
}
#[cfg(not(feature = "std"))]
{
f.write_str("TryInitError(())")
}
}
}
impl fmt::Display for TryInitError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
#[cfg(feature = "std")]
{
fmt::Display::fmt(&self.inner, f)
}
#[cfg(not(feature = "std"))]
{
f.write_str("failed to set global default subscriber")
}
}
}
#[cfg(feature = "std")]
impl Error for TryInitError {
fn source(&self) -> Option<&(dyn Error + 'static)> {
self.inner.source()
}
}
|
